Redundancy Control of a Master-Slave Manipulator with a Redundant Slave Arm

Abstract

We have developed a master-slave manipulator with a 7 DOF slave arm and the redundancy control of the slave arm has been investigated. In the redundancy control, the redundancy is used not to avoid singular attitude but to compensate the loss of freedom at singular attitude. The developed redundancy control enables the movement at singular attitude and avoids each joint limit as much as possible so that the slave arm can move widely. The desired position and direction of the slave arm are transformed to the desired joint angles by the pseudo-inverse Jacobian. The redundant item is set to maximize the value of a performance index. The wrist joint of the slave arm consists of R -P-R, so a coincidence of 2 roll axes is the singular configuration. The performance index is set as the difference between the desired hand orientation and the current forearm orientation when the attitude of the slave arm is near the singular configuration so that the desired direction can be achieved by the wrist direction even at the singular configuration. Finally, the validity of the developed control method has been confirmed by experiments.